Mark Durney's "Reevaluating Art Crime's Famous Figures" published in the International Journal of Cultural Property

Mark Durney, the creator of the ARCA Blog and of Art Theft Central, studied history (undergraduate) at Trinity College in Hartford, CT, and archaeology (masters) at the University College of London. Noah Charney interviewed him in 2011. Mark spoke about the importance of "Collection Inventories" at ARCA's International Art Crime Conference that same year. Mark previously served as ARCA's Business and Admission's Director.

Here's the abstract:

This article seeks to demonstrate that the figures used to describe the size and scope of cultural property crimes—that it is a $6 billion illicit
industry and that it ranks among the third or fourth largest criminal enterprise
annually—are without statistical merit. It underscores the ambiguities inherent
in the figures and uses the 2003 theft of the Duke of Buccleuch’s painting by
Leonardo da Vinci, Madonna of the Yarnwinder, to illustrate the difficulties
related to establishing monetary estimates for cultural property crimes. It calls
for a more empirical approach to measuring the magnitude of the problem on
the part of cultural property crime experts. Finally, it examines the reporting
methods of the world’s largest cultural property crimes law enforcement
agency, the Comando Carabinieri per la Tutela del Patrimonio Culturale, in
order to provide a model for others to follow in the effort to communicate the
severity of the problem and to increase its financial, social, and political
support.

The article discusses cultural property crime data, the "multibillion dollar industry", and the value of Leonardo da Vinci's Madonna of the Yarnwinder stolen in Scotland in 2003 and recovered four years later:

The example of Leonardo da Vinci’s Madonna of the Yarnwinder, which was stolen
in a daytime raid from Drumlanrig Castle, Scotland, in 2003 and recovered in
2007 underscores the difficulty with estimating an object’s value in order to account for its contribution to the annual illicit cultural property trade figure. For
tax reasons, the Duke of Buccleuch insured the painting for only a quarter of its
1996 valuation—£15 million.27 Other estimates for the painting’s value published
by the media ranged from £20 to £50 million.28 Immediately after the theft, the
Buccleuch’s insurer offered a £200,000 reward, which was later increased to £1 million. In 2007, Robert Graham and John Doyle, private investigators who operated
a stolen property recovery website called Stolen Stuff Reunited, were contacted by
mysterious intermediaries known only as J and K, who had access to the stolen da
Vinci. According to court records, the painting had been used as collateral for a
£700,000 property deal and the individuals, who accepted the painting as security
sought to recoup their money. Graham and Doyle contacted their solicitor Mar-
shall Ronald. Ronald involved Glasgow solicitors Calum Jones and David Boyce in
order to ensure the recovery dealings were legal under Scottish law. Ronald, on
behalf of his clients, negotiated with the intermediaries to return the painting for
£350,000. During the recovery process he notified the Buccleuch’s insurance loss
adjustor, Mark Dalrymple, in order to return the painting through an informal
mediation process.29 In negotiations between Dalrymple and John Craig, who was
an undercover police officer posing as the Buccleuch’s representative, Ronald requested a total of £4.25 million as a reward and to cover his and his clients’ expenses.30 However, before negotiations evolved any further, police arrested Ronald,
Graham, Doyle, Jones, and Boyce and charged the group with conspiring to extort
£4.25 million from the Buccleuch family for the painting’s return.31 After an eight-
week trial at the High Court in Edinburgh, a not-proven verdict was returned on
Ronald, Graham, and Doyle. Both Jones and Boyce were found not guilty of the
same charge. It was later revealed by the Scottish Legal Aid Board that £984,636
was paid to cover legal expenses of all the accused, which was a loss incurred by
the Scottish taxpayer.32

As illustrated by the case of the Madonna of the Yarnwinder, illicit art’s monetary value can be based on its insurance claim, its value as collateral in illicit
transactions, or the cost of its recovery. Also, its value can be based on its estimated value. In this example, the painting’s estimated value would be difficult to
determine due to the fact that it is a rare work by one of history’s most famous
artists and has not been on the market since the eighteenth century when it was
first acquired by the Buccleuch family.

Italy’s Comando Carabinieri per la Tutela del Patrimonio Culturale, which is the
largest cultural property law enforcement unit in the world and has been very
successful at policing such crimes since 1969, maintains a vast stolen cultural
property database called Leonardo.45 The Carabinieri publish an annual report
titled Attivita’ Operativa, which provides theft and recovery data as well as con-
tributes insights into its cultural property protection efforts over the past year.46
The Carabinieri’s success at recording, publishing, and analyzing crime data is
likely due to the fact that it has a uniform reporting system in place across its 14
regional units. In order to measure the unit’s performance, it compares the latest
data with that from the previous year. While the annual report includes a mon-
etary estimate of the total value of cultural objects recovered or seized, it supplements the data with more significant figures including those related to cultural
objects recovered or seized by the Carabinieri.47 Also, the Carabinieri’s annual
report incorporates the number of individuals referred to the judicial system from
its actions; a detailed account of its preventive activities carried out, such as the
review of businesses, markets, and fairs, as well as the inspection of the safety
and security measures at museums, libraries, state archives, and archaeological
sites; and a summary of its training activities with domestic and foreign law enforcement organizations.48

In addition to providing in-depth recovery data that is even segmented by re-
gion, the Carabinieri’s report includes annual theft data. For example, there were
817 cultural property thefts reported in 2010 to the Carabinieri.49 The juxtaposition of the reported thefts against the number of objects recovered or seized pro-
vides statistical evidence that leads one to conclude that a substantial number of
thefts are underreported or unnoticed. This method of reporting better conveys
the severity and scope of the illicit cultural property trade than any dollar amount
could achieve.